This book tells the story of the Manhattan Project’s three principal sites: Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico. Using thousands of documents from house plans to medical records, Hales investigates the work at all three sites and the lives of the people. He traces the history of the project from its origin, to the construction of the bombs, to their consequences. He also explores the various occupations of the hundreds of thousands of people employed at these sites between 1942 and 1946. The author focuses on showing the reader that “the District’s goal was not to produce communities, but to produce weapons” (introduction), and he explains the military’s and the bureaucracy's often underhanded ways of accomplishing this task.